Support PluginWatcher in Windows

Signed-off-by: Deep Debroy <ddebroy@docker.com>

pkg/kubelet/util/util_unix.go

@@ -135,3 +135,20 @@ func LocalEndpoint(path, file string) (string, error) {
 	}
 	return filepath.Join(u.String(), file+".sock"), nil
 }
+
+// IsUnixDomainSocket returns whether a given file is a AF_UNIX socket file
+func IsUnixDomainSocket(filePath string) (bool, error) {
+	fi, err := os.Stat(filePath)
+	if err != nil {
+		return false, fmt.Errorf("stat file %s failed: %v", filePath, err)
+	}
+	if fi.Mode()&os.ModeSocket == 0 {
+		return false, nil
+	}
+	return true, nil
+}
+
+// NormalizePath is a no-op for Linux for now
+func NormalizePath(path string) string {
+	return path
+}